He doesn't swim naked, so he takes the summon anyway.
"Oh. In a broader sense, my business here is that your civilization is collapsing and I would like to see if any of it is salvageable and compatible with people other than your species continuing to be alive, and do my best to help salvageable parts survive."
"I also want you to stop murdering people, which you seemed to be doing when I looked."
Cam pulls up some of the video he took of the ritual sacrifice. "Ring a bell?" he asks, displaying it.
"Because a lot of people have died today, entirely too many, and while if you absolutely have to kill people your choice of targets is not bad, I doubt very much that you absolutely have to kill people."
"Yes," sighs Cam. "Yes, I am. Your civilization was rigged to explode as soon as it met someone it couldn't kill, and it can't kill me."
"I don't want to destroy you but under the circumstances I can't trust you, so leaving you alone will have to wait until I know more about what you're up to."
"I want to learn more about what you want to do, if it's not 'destroy filth creatures'. And I would like you to stop killing people. Maybe they're all so obsessed with purity that they'll kill themselves, but if you help them that seems like it risks bycatch of some who do not in fact want to die."
"So you don't think you can hold order under conditions where organized dissent exists?"